CHECK_C_SOURCE_COMPILES("
    int main()
    {
      extern void __attribute__((weak)) foo(void);
      return 0;
    }"
    HAVE_WEAK_SYMBOL
)

CHECK_C_SOURCE_COMPILES("
    int main()
    {
      extern void __attribute__((weak)) foo(void);
      return 0;
    }"
    HAVE_WEAK_SYMBOL
)

CHECK_C_SOURCE_COMPILES("
    int main()
    {
      extern void __attribute__((weak)) foo(void);
      return 0;
    }"
    HAVE_WEAK_SYMBOL
)